Empyema caused by Streptococcus constellatus: a case report and literature review

BACKGROUND: Streptococcus constellatus is a member of Streptococcus anginosus group (SAG) that tends to cause pyogenic infections in various sites. However, Streptococcus constellatus is easily ignored by routine clinical laboratory tests for its prolonged anaerobic culture environment. CASE PRESENTATION: A 71-year-old man was admitted to our hospital due to productive cough, fever, chest pain and shortness of breath for 3 weeks. Chest computed tomography showed patchy opacities and right-sided pleural effusion, so a chest tube was inserted and purulent and hemorrhagic fluid was aspirated. The routine etiological examinations of the pleural effusion were all negative, and next-generation sequencing (NGS) detected Streptococcus constellatus. Intravenous piperacillin-tazobactam 4.5 g every 8 h was used accordingly. The patient recovered and subsequent chest computed tomography confirmed the improvement. CONCLUSIONS: We reported a case of empyema secondary to Streptococcus constellatus infection, which was identified by NGS, instead of bacterial culture. This case highlights the utility of NGS in detecting pathogens negative in traditional bacterial tests.